Dual-Booting | Linux(R) Desktop Garage

What Is Dual-Booting?

Dual-booting is the term commonly used when installing two separate operating systems on the same computer. You can partition a single drive with one operating system on each, use one hard drive for each operating system, or spread things out among a few drives. For example you could dual-boot Linux and Windows or Linux and Mac OS.

Here is how dual-booting works. Your hard drive has on it what is called the Master Boot Record (MBR). The Master Boot Record is located in the first sector of your hard disk. The record contains your partition table as well as information to identify where and how your operating system will boot. Normally, with one operating system, the MBR just shoots right into the OS that you have on your hard disk. However, when you are dual-booting, the MBR first makes a stop at a program called a boot loader. The boot loader gives you a menu of choices so that you can choose which of the operating systems on your hard disk you want to boot into. If you make no choice, the default choice is chosen automatically after a set number of seconds. The labels for the operating systems, which one is the default, and how many seconds to wait are all configurable.

Why Dual-Boot?

A good portion of the rest of the world is using other operating systems, mostly Windows and Mac OS. Those people will send you files, design Web sites, provide multimedia content, write software, and do most everything else with those other two more popular operating systems in mind. Linux can handle most of that, but sometimes you will need to use Windows or Macintosh. You might receive an office document with formatting that looks funny when you open it in Linux. You might visit a Web site that has a lot of multimedia content that would just be too much trouble to make work in Linux for the few moments that you will be there. You might have a deep, abiding need to play the latest first-person shooter game that will not run in Linux. You might want a gradual change to your new OS. You might get the point by now with all these repetitive sentences I have just given you.

The Boot Loader

When you are dual-booting, the boot loader is a program that serves as a pit stop in the boot process for you to choose which operating system on your computer you want to boot into. The most popular boot loaders for use with Linux are GRUB, LILO, and Yaboot.

GRUB and LILO run on PCs. LILO is the older choice, but GRUB is quickly overtaking LILO as the best choice for a boot loader. GRUB is the newer software, with some fixes of problems that previously came up in LILO. Mandrake still uses LILO as the default in 10.0, but you can switch it to use GRUB in the Summary screen. If you don't switch the boot loader in Mandrake from LILO to GRUB, nothing bad will happen. Choosing either LILO or GRUB will not make much difference for most users.

Yaboot is almost your only choice in a boot loader to run on Apple machines. Yaboot is certainly the reliable, tested boot loader that has been around for a while. Yaboot is text only and might look a little funny sitting in the upper-left corner of your screen in small text. Yaboot is a minimalist boot loader without a GUI or a lot of bells and whistles.

Steps for Dual-Booting with Windows

Look at what you have now. Is Windows already installed, or can you start from scratch? The best plan is to start from scratch. If you have a previous Windows install with programs and data that you are too in love with to back up and reinstall, you will have to try to resize your Windows partition. This is the more difficult choice.

UNDER THE HOOD

PREPARE TO SHARE

You might want to format the Windows partition with the Fat32 file system so that you can access data from your Windows partition with Linux. There are options for reading and writing with an NTFSpartition, but the options are fairly new, kind of buggy, and none too fun. If you plan to do a lot of file sharing, save yourself an ulcer and format the Windows partition with Fat32.

Back up everything. If you are not the kind of person who regularly backs up your data, start now. Hard drives can crash. Power lines can surge. Computers lose things. Especially back up any of your data from Windows before beginning this process.

Plan the partitions. If you need to resize a Windows partition, two options are a commercial program called Partition Magic and a DOS program called FIPS. (FIPS has many limitations; you should really try to use Partition Magic.) Both URLs are in the "Links" section at the end of the chapter. Always defrag your Windows partition before resizing it. For file sharing between partitions, a good idea is to create a third partition as a data partition. See "Sharing Files Between OS Partitions," later in this chapter, for more detail. Remember to give Linux at least 5GB just so that you have room to play with.

Install Windows first. Windows likes to be in control. Windows takes over the Master Boot Record during installation, with no choice to do otherwise. If you are installing XP or Windows 2000, use the option in the install to put Windows on one partition and leave the rest of the intended Linux space as free space. When installing Windows 95 or 98, use fdisk (a DOS utility usually available on a Windows boot floppy) to create the partition you will use for Windows, and leave the rest of the drive as free space.

Start your Linux install. Read up on the details in the installation section below. While moving through the installer screens, pay attention to what device the partitions are on; note them down, in case any of the OS partitions are not properly detected (i.e. Windows on /dev/hda1 and the Linux root partition on /dev/hda3).

Set up the boot loader. This is done during the installation. Whether you use GRUB or LILO, follow the directions to set up the labels and default OS to boot into. The choices automatically are detected for you, but you can add or edit if something is missed.

Back Up Your Life

I am constantly surprised that so many experienced computer users do not regularly back up their data and files. I might be a little bit of a backup Nazi, but it is only because I know how easy it is to have all your files one day and then have an inaccessible hard drive the next.

I have everything digital. I ripped all of my music CDs to digital files. I pay bills online. I no longer know what sticky notes are. All the family photos are scanned in. I blog the events of my life on a Web site. I think my dog might even be digital. More and more, we are moving the documents of our entire lives over to our computers. Aren't those things important enough to back up?

The whole process needs to take you only fifteen minutes at the beginning of every month. Just copy everything that you value onto a rewriteable CD, a Zip disk, a CDR, another computer in your house, an online service, or anything else you can use.

Steps for Dual-Booting with Mac OS

Plan the partitions. If MacOS is already installed, it's going to have to be reinstalled. There is no easy way to resize an existing Mac partition. When you go through the install of MacOS, a screen for creating partitions appears. Leave the intended Linux space as just free space. If you can, remember to give Linux at least 5GB, just so that you have room to play with.

Install Mac OS first. Just as with Windows, MacOS wasn't expecting to share you with any other OS, so there isn't an option for anything such as a boot loader. MacOS takes over the MBR.

Start your Linux install. Read up on the details in the following installation section. While moving through the installer screens, pay attention to what device the partitions are on; write them down, in case any of the OS partitions are not properly detected (for example, MacOS on /dev/hda1 and the Linux root partition on /dev/hda3).

UNDER THE HOOD

CD BOOT

Your computer might not be set up to boot from a CD. If it is not, on PCs, you need to go into your BIOS to change the boot device order. On most systems, you press Delete, F1, or F2 to enter theBIOS (just look onscreen for a prompt of what key to press). Follow the directions in your BIOS to find the boot device section and make sure that your CD-ROM drive will boot before your hard disk. On newer Apple hardware, you just hold down C to boot from a CD.

Set up the boot loader. A program called Yaboot is the most likely option for your boot loader. Follow the directions to set up the labels and default OS to boot into. The choices automatically are detected for you, but you can add or edit if something is missed.

Sharing Files Between OS Partitions

When you dual-boot your system, having access to the files on your other partitions from within Linux can be helpful. This is a one-way street, though. Linux can see Windows partitions, but Windows cannot see Linux partitions. I think there is some denial going on there.

Sharing the Windows partition with Linux is not a clean way to do things. Headaches are involved with mounting the Windows partition so that it will be writeable for your regular user account. In addition, when mounting your Windows partition as writeable, you run the risk of deleting or moving files that Windows needs. When sharing files with your Windows partition, you need to be aware of what you are doing and always keep backups.

A cleaner way to share files between Linux and Windows or Mac OSX is to have a third (you can think of it as the middle) partition on your system to serve as the sharing space. The size depends on what you want to do. I share the 5GB of MP3s that I have between two OSs. Determine how much space you need for the data that you will want to share, and create the partition.

If you are running Linux on a Mac, the options for viewing a MacOS partition from Linux are a little complex for new users. The options to both read and write to your Mac partition are even shakier. Even though OS X is UNIX based, the two OSs and file systems do not play well together. Keep an eye out online. Every problem gets solved eventually in the Linux community.